organic synthesis Flashcards
organic synthesis
process of making organic compounds from simpler starting materials
what do we call the compound you want to make
target molecule
what are intermediate compounds
compounds that you make on the way to the target molecule
what is the purpose of a mechanism
they show how electrons rearrange when a chemical reaction happens
is breaking bonds endo or exothermic
endo
when bonds are formed is that endo or exothermic
exo
how to identify a substitution reaction
start with 2 molecules end up with 2
how to identify a addition reaction
start with 2 molecules end up with one
how to identify an elimination reaction
start with 1 molecule end up with 2 molecules
how to identify a redox reaction
is something gaining or loosing oxygen/ forming double bonds to Oxygen
substitution reaction
a chemical reaction in which an atom or group of atoms in a molecule is replaced by another atom or group of atoms
what are the 2 substitution reactions
halogenation of alkanes
esterification
uses of halogenated alkanes
they do not support combustion so are used as fire extingushers
free radical
an atom/ molecule/ group of atoms that contain s unpaired electron
how are free radicals presented
a dot
how reactive are free radicals
extremely reactive as they do not have a stable outer octet
homolytic fission
each atom joined by the bond keeps one of the 2 electrons in the bond
write the mechanism for the monochlorination of methane
initiation
propagation
propagation (chain reaction step)
termination
evidence for free radical substitution
takes place under UV light- suggests that a free radical mechanism occurs where Cl2 is split into 2 chlorine free radicals
for every photon of light absorbed, thousands of chloromethane molecules form- evidence for chain reaction
small amounts of ethane formed- methyl free radicals combine to form ethane
adding a source of free radicals eg tetraethyllead speeds up the rate of reaction- this decomposes to produce methyl radicals which then increase the rate of the reaction
if an inhibitor is added the rate of the reaction slows down-the inhibitor combines with free radicals to stop the chain reaction from occuring
what is hydrolysis?
the reverse reaction of esterification
ie
ester + water —–> alcohol and carboxylic acid
saponification
base catalysed hydrolysis of esters with a carboxylate salt is formed
describe hydrolysis
a chemical reaction where something reacts with water
the ester reacts with OH- and H+ and the ester breaks apart
a base is a very effective reactant to hydrolyse an ester. the most commonly used us sodium hydroxide
addition reaction
a reaction where 2 or more molecules react together to form a single product
use of 1,2-dichloroethane
used to make PVC
use of 1,2-dibromoethane
used to fumigate logs for termites and beetles
use of ethanol
solvent